Application of liquid treating material to strip material

ABSTRACT

579.074. Coating yarns .&amp;c. INTERNATIONAL LATEX PROCESSES, Ltd. Jan. 6. 1944, No. 229. Convention date, .Jan. 19, 1943. [Class 140] A wire, thread, or cord 1 to be coated or impregnated with a liquid such as varnish, enamel, rubber solution or dispersion is drawn upwards through bottom and top openings 2 and 4 in a partially evacuated chamber 3 containing the treating liquid 6 in the bottom portion 5 thereof, the partial vacuum serving to prevent escape of liquid through the bottom opening 2. and to maintain a replenishing supply of treating liquid, e.g., from a constant-level reservoir 10. The partial vacuum may be produced by the ejector action of a stream of compressed air introduced at 14 into the annular space between a tube 11 forming an upwards extension of the top opening 4, and a surrounding tube 12. The bottom portion 5 containing the treating liquid may be of reduced diameter, and the base 7 may be a stretchable rubber membrane which facilitates passage of splices. The opening 2 in the base 7 is of larger diameter than the wire and does not act as a wiping or sealing means. The coating may be gelled and dried by an electric heater 15. A number of wires or threads may be coated by providing a number of aligned top and bottom apertures in a single chamber, or superposed coatings may be applied on a single wire by passing it through several similar coating devices. Rubber threads may be produced by coating wires having one or more sharp edges, and stripping off the coatings as described in Specification 422,403.

y 1944- R. B. FROST 2,348,289 APPLICATION OF LIQUID TREATING MATERIAL TO STRIP MATERIAL Filed Jan. 19', 1943 mgwy ATTORN Y Patented May 9, 1944 APPLICATION OF LIQUID TREATING MATE- RIAL TO STRIP MATERIAL.

Raymond B. Frost, Rutherford, N. J., assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application January 19, 1943, Serial No. 472,849

8 Claims. (c 91-55 This invention relates to the application of liquid treating materials to strip material such as wire, threads, cords, and the like.

In coating wire with varnish, enamel, rubber latex, or solutions or aqueous dispersions of rubber or rubber-like materials; and in coating or impregnating threads or cords with dispersions or solutions of treating material, the usual method of applying the liquid treating material to the wire, thread, cord, or other strip material, is to lead-the strip material vertically downward into a tank of the liquid treating material, pass it around an immersed sheave and then lead the strip material out vertically again to a drier or the like. The objections to this method are the large amount of liquid treating material necessary and the excessive tension on the strip material required to overcome friction of the sheave bearings. Where the sheave is immersed less than one-half its diameter in the treating bath in order to keep the sheave-Journals or bearings out of the bath, the strip material leaves the sheave surface on a point of contact above the surface of the bath producin irregularities in the coating.

Various methods have been suggested for applying liquid treating materials to strip material 1 by passing the wire or thread vertically upwards through a bath of the treating material, the strip material passing through openings in the bottom of the chamber or container which holds the body of the treating material. To keep the treating liquid from flowing out of the jqpenings in the bottom of the container or tankirthrough which the strip material passes, wiping or sealing elements have been provided to make close contact with the strip material as it passes through the opening, thereby holding the treating material in the tank. Such wiping or sealing elements wear out readily, and when the treating liquid is pressure sensitive, as for example, .rubber latex, the friction of the strip material passing through the wiping element tends to cause coagulationflat the seal, resulting in uneven coatings with the for mation oi lumps of coagulum on the surface of the strip material. f It has also been suggested to keep the liquid from flowing out of the apertures in the bottom of the tank by relying solely on capillary action or adhesion of the liquid, but this is unsatisfactory because slight changes in temperatures and in the composition of the liquid may cause great changes in the viscosity and other physical properties of the liquid upon which reliance must be had to maintain the seal. Another suggestion has been to maintain air pressure beneath the apertures, but in this method air which is a diagrammatic view of a preferred em-.

bodiment of the invention.

According to the present invention, a small 001- umn of the liquid treating material is prevented from flowing out of an aperture in the bottom of the chamber by maintaining a partialwacuiim within the chamber, as by providing an air ejector surrounding an aperture in the top of the chamber which is aligned with the aperture in the bottom of the chamber and through which apertures the strip material passes. The air ejector at the top of the treating chamber draws air from inside the chamber through the top aperture, creating a partial vacuum in the chamber so that the treating material in the bottom of the chamber will be prevented, by the atmospheric pressure on the bottom of the liquid column, from flowing out of the bottom opening. Thus the strip material is free to pass up into,' through, and out of the treating material to the surrounding space without the use of a mechanical seal, whilethe treating liquid-is prevented from flowing out of the bottom opening.

Referring more particularly to the drawing, there is illustrated therein an apparatus for coating a single wire with a rubber dispersion, such as latex. Several of such units may be used in cascade where multiple coats of the latex are to be applied to the wire. Similarly, a number of wires may be made to pass through an apparatus by providing the requisite number of aligned top a: :1 bottom apertures as shown in the'illustration. In the drawing, a wire I passes upward in vertical direction through an ingress opening 2 in the bottom of the chamber 3 and out through an latex 6 which is to be maintained in the bottom of the chamber. The base I of the well 5 is'preterably of rubber so that where wires are spliced together, the opening 2 will yield when the splice I,

and sealing surface. Latex is kept supplied to the well 5 by the tube 8 connected to the side of the well intermediate of the column of latex as at 9,

the tube 8 acting as a syphon feed from a latex reservoir Ill. The top opening 4 is preferably extended upward in the/form of a tube II. A tube l2 surrounds tube H and is sealed to the top of the chamber 3 as at l3. An inlet tube I4 is connected to the tube l2 adjacent to the top of the container 3 for entrance of compressed air which in flowing out of the space between the tubes ll and I2 draws air along with it through the opening 4 and out of the tube I l, as shown by the arrows, thereby producing a partial vacuum in the container 3. A radiant heater l5 for gelling and drying the latex may be provided between the bottom and top openings of the chamber.

In operation, as may be 'clearly seen from the drawings, the wire I enters the treating chamber comes gelled or dried by means of the radiant. heater IS. The wire passes out through the opening 4 in the top of the container. Air under pressure is introduced through the entrance tube l4 into the tube l2, and as the air flows upward past the mouth of tube II, it acts as an air ejector carrying with it air drawn from the inside of the chamber.3 through the tube H. In this manner a' partial vacuum is maintained in the chamber 3,- preventing latex 6 in the bottom of the chamber from flowing out through the bottom opening 2, by virtue 'of the atmospheric pressure acting on the latex at the opening The apparatus may be used with various liquid treating materials and for treatment of various kinds of strip materials, such as wire, thread, cords, and the like. adhesion of the treating liquid play an important part in supporting the column of liquid 6 in the well 5. The larger the opening in the bottom through which the wire passes, the greater is the danger of rupture of the lower surface of the treating material in the well. Therefore, .for reasonable assurance of successful operation, the radial clearance between the wire and the sides of the opening 2 should generally not be greater than 3 of an inch with low viscosity liquids. The wire, passing in an upward direction; produces an upward lifting force or drag acting on the liquid, resulting from the combined effects of The surface tension and be stripped from the wire to produce one or more rubber threads.

In view of the many changes and modifications that may be made without departing from the principles underlying the invention, reference should, be made to the appended claims for an understanding of the scope of the protection afforded the invention.

Having thus described my invention, what I claim and desire to protect by Letters Patent 1. Apparatus for applying liquid to strip material comprising a chamberadapted to hold a body of treating liquid in the bottom thereof, said chamber having top and bottom openings for the passage therethrough of strip material, means for withdrawing air from the interior of the chamber so as to create a partial vacuum in said chamber, whereby treating liquid in the bottom of the chamber will be prevented by the pressure of the atmosphere from flowing out'of said bottom opening, and means for supp1ying treating liquid to a body of treating liquid in the bottom of said chamber.

2. Apparatus for applyin liquid to strip material comprising a chamber adapted to hold a body of treating liquid in the bottom thereof, said chamber having top and bottom openings for the passage therethrough of strip material, an air ejector associated with said chamber for withdrawing air from the interior of the chamber so as to create a. partial vacuum therein, whereby treating liquid in the bottom of the chamber will be prevented by the pressure of the atmosphere whereby treating liquid in the bottom of the container will be prevented by the pressure of the atmosphere from flowing out of said bottom opening, and means for supplying treating liquid to a body of treating liquid in the bottom of said chamber. v

4. Apparatus for applying liquid to strip material comprising a chamber adapted to hold treating liquid in the bottom thereof, said chamber the viscosity of the treating liquid and the adhesion between the treating liquid and the stripmaterial. The chamber 3 may be of approxi 'mately the same diameter as the bottom well 5 times. If the treatment results in a coating as illustrated in the drawing, it may be a permae tion on wire. If desired, such a wire may have one or more sharp edges so that the coating may nent coating, as for example, a rubber insulahaving top and bottom openings for the passage therethrough of strip material, an air ejector associated with said top opening in such a manner that 'the passage of air under pressure through the ejector will draw along air from the interior of the chamber through said top opening to create a partial vacuum in the chamber, whereby treating liquid in the bottom of the chamber will be prevented by the pressure of the throughsaid top opening to create a partial vacuum in the chamber, whereby treating liquid in the bottom of the chamber will be prevented by the pressure of the atmosphere from flowing out of said bottom opening, and means for supplying treating liquid to a body of treating liquid in the 6 bottom of said chamber.

6. Apparatus for applying liquid to strip material comprising a chamber adapted to hold treating liquid in the bottom thereof, said chamber having top and bottom openings for the passage therethrough of strip material, means for withdrawing air from the interior of the chamber so as to create a partial vacuum in said chamber, whereby treating liquid in the bottom of the chamber will be prevented by the pressure of the atmosphere from flowing out of said bottom opening, a heating device intermediate said openings for heating strip material during its passage through said chamber, and means for supplying treating liquid to a body of treating liquid in the the ejector will draw along air from the interior of the chamber through said top opening to create a partial vacuum in the chamber, whereby treating liquid in the bottom of the chamber will be I prevented by the pressure of the atmosphere from flowing out of said bottom opening, a heating device intermediate said openings for heating strip material during its passage through said chamber, and means for supplying treating liquid to a body of treating liquid in the bottom of said chamber.

8. Apparatus for applying liquid to strip material comprising a chamber adapted to hold treat ing liquid in the bottom thereof, said chamber having top and bottom openings for the passage therethrough of strip material, an air ejector surrounding said top opening so that the passage of air under pressure through the ejector will draw along air from the interior of the chamber through said top opening to create a partial vacuum in the chamber, whereby treating liquid in the bottom of the chamber will be prevented by the pressure of the atmosphere from flowing out of said bottom opening, a heating device intermediate said openings for heating strip material during its passage through said chamber, and means for supplying treating liquid to a body of treating liquid in the bottom of said chamber.

RAYMOND B. FROST. 

